1. Field of the Invention
The present invention relates to a sealing structure for an electronic element section such as a display element, a semiconductor circuit element, etc., and more specifically, the present invention relates to a sealing structure with a barrier membrane for a display device, an electronic apparatus, and an electronic element section, as well as to a fabrication method therefor. The description of the present invention herein specifically pertains to an organic EL display device as an example of preferred applications; however, the present invention is not limited to the organic EL display device.
2. Background Art
In recent years, color display devices, which contain a plurality of display elements each of which comprises a pair of electrodes and active layers, such as a hole-injection layer/transportation layer, a luminous layer, etc., being sandwiched between the pair of electrodes, have been developed, and specifically, organic EL (electroluminescent) display devices, in which organic luminous material is used for the luminous layer, have been developed. The organic EL display device comprises active matrix circuits formed on a substrate made of, for example, glass, plastic, etc., electronic element sections formed on the active matrix circuits in a matrix pattern, and a “sealing can” for covering and sealing the electronic element section.
The “sealing can” is made of glass, metal, etc., in a box shape. The sealing structure using the “sealing can” is configured such that the “sealing can” is adhered to the periphery of the substrate using adhesive while containing the display elements therein. The “sealing can” also contains an inert gas such as nitrogen, argon, etc., in a sealed manner along with a getter substance for absorbing water and oxygen so that permeation of water and oxygen into the display elements are prevented, and the luminous layers are prevented from being deteriorated.
The overall thicknesses of conventional display devices are typically 2 to 5 mm, in which approximately 1.5 mm, at least, is occupied by the “sealing can”. Because the display elements must be contained in the “sealing can” without contacting thereto, and a sufficient space for containing the getter substance or the like must be provided in the “sealing can”, the thickness of the sealing structure must be increased as the sizes of the display elements increase in order to ensure sufficient strength thereof.
Moreover, because adhesive is used to adhere the “sealing can” to the substrate, a region for applying the adhesive must be occupied along the periphery of the substrate, and as a result, the size of the region for display, in which the display elements are arranged, is reduced with respect to the overall size of the display device, whereby a problem is encountered in that the exterior design of the display device is constrained when the display device is employed as a display portion of an electronic apparatus such as a portable telephone or the like. In addition, an allowable space must be occupied between the region for applying the adhesive and the region for display because the adhesive may spread out, which leads to another problem in conventional display devices in that the size of a so-called frame region, i.e., a region formed by the allowable space and the region for applying the adhesive, cannot be reduced. Furthermore, if the size of the region for applying the adhesive is reduced in order to enlarge the region for display, the barrier properties of the display device against water and oxygen may be degraded, and as a result, the luminous layers may be deteriorated (i.e., the operative lives of the luminous layers may be reduced).
Moreover, because the adhesive may not be uniformly applied to the substrate, or the adhesive may not function sufficiently, the region for applying the adhesive may not be delimited from the region for display in a manner intended, and the barrier properties of the display device may vary depending on location, which leads to a further problem in that the reliability of the display device is degraded.
Furthermore, when such a structure using a “sealing can” is employed, it is not possible to produce a top emission type display element, in which display light is emitted in the opposite direction compared with a conventional device so that a greater aperture ratio is obtainable, because the getter substance or the material forming the “sealing can” will not allow the display light to pass.